1998 Chevy Monte Carlo EGR problem?

Ok I ran it a bit more and got the original symtoms again, except worse. I went about 4 miles to the gas station, when I pulled in, it died. I put 5 bucks in the tank then I was gonna ride softly to autozone since at lower rpms it seems to be fine, well not now. I pulled out of the gas station and it started bucking at around 1500 rpm, the tach would drop and jump all over the place. So I turned around and drove home. Even with my foot off the gas and cruising it would want to die, the tach would drop 500-600 rpm and I still couldn't get it to go over 2500 rpm, also when I pressed the gas sometimes it would seem to do nothing, Obviously this problem gets worse the more warmed up the car is, and first thing in the morning with dew on the car it managed to get to 6k rpm. I read somecodes and got a new freeze frame data from when I unplugged the MAF I think tho I may be wrong, heres the info it put out tho.

MAybe its an electrical wiring problem? I don't know.

P0102

Load 1.1%

2610 RPM

MAP sensor 37 KPA

Air Flow Rate 1.90 GR/sec

Throttle position 16.4%

Coolant temp 197 degrees.

Fuel trim same as above

Fuel system open.

If I goto I/M monitor it says OK or N/A or INC, no fails.

It threw p1676 again as well I guess I need to check that wiring as well.

Hope some of this helps, and someoen can figure out what -96.7% short term 3 fuel trim is.

I got another p1676 code so I'm really starting to think this has something to do with fuel tank vapors constantly flowing into the vehicle maybe?

I noticed my fuel trim hasn't changed in this code, I read that the PCM doesn't adjust anything untill the engine goes into closed loop? So why would my engine not meet closed loop requirements?

Just an OBD II reader that I borrowed from autozone.

I've been reading up a bit and I don't think my car is going into closed loop.

Every time I read freeze frame data from any code, my fuel trim is exactly the same. It hasn't tried to adjust it at all.

My thermostat appears to be working because the coolant temperature is different in each freeze frame and its been as high as 197 degrees, I'm not sure how to ttell if the car has gone into closed loop or not?

Possibly my o2 sensor is bad, I pulled it out to check if I was having an issue with backpressure from a bad cat and sprayed it with MAF cleaner and stuff, ran the car with it out confirming that the cat wasn't clogged as it ran the same with no backpressure.

In the freeze frames it says "FUEL system open" does that mean I'm still in open loop? That is the same on every code I scan as well.

I'm under the impression at some point my car set some really off fuel ratio information, then got stuck in open loop and has been using that information ever since and not going back into closed loop.

I don't know just throwing it out there.

I was doing the EVAP purge valve circuit fix and I was getting 0 amps on the connector at the PCM, and did get voltage at the connector to the purge valve(I think its the purge valve, it's located above the o2 sensor below the ICM on the back of my engine?) And I got voltage there. So I think it's leaning towards a short or a bad purge valve maybe? But I don't think that has to do with my engine going closed loop does it? I blew the fuse to the purge valve by trying to test amps on the power feed wire on the connector to the purge valve, so I'm getting good amperage there lol.

Sorry just shooting some stuff out there to see what you think.

OK I Just took it out on the road, and got a p0401 code, EGR FLOW INSUFFICIENT.

I got this error a few times before, so I used carb cleaner and cleaned the EGR vacuum out best I could, and got a new EGR valve. Ok now I took the throttle body off (that was a pain due to a very poorly designed mounting bolt on the bottom right of the throttle body), cleaned the EGR out VERY good from the inside of the intake plenum, cleaned my throttle body out as well.

Unfortunately at some point while my throttle body was off I broke my throttle cable so now I need to replace that, any ideas? I musta kinked the wire or something because one tiny wire of the braided cable broke and started jamming up the cable so it wouldn't go back to idle, I tried pulling that off but 6 braided cords later its hanging by a single braid of wires and it still jams up so not much I think I can do other than replace it. I couldn't find an OEM replacement tho, just a universal kit? Any suggestions?
Freeze Frame data:

Throttle Position - 0.3%

Engine RPM - 1136

Air Flow Rate - 4.67GR/sec

MAP Sensor - 30 KPA

Coolant Temp - 177 degrees F

Short term fuel trim 1 - 0%

Long Term Fuel Trim 1 - negative 13.3%

Short Term Fuel Trim 3 - 50%

Long Term Fuel Trim 3 - negative 45.2%

Vehicle speed - 45mph

Fuel System 1 - closed

So It finally went into closed loop and tried to adjust, but it was still misfiring. Note I took this drive with the evap purge valve unplugged. I was trying to go through the OBD II GM driving cycle I read but I didn't have enough space

I did the repairs and it said to replace evap purge valve. One thing that was weird is when I started the tests the connector at the PCM read battery voltage, but now after I've done all the tests If I goto read voltage at the PCM connector I get none? But I still get battery voltage at the purge valve connector.

Well im going to get a purge valve tomorrow but I doubt that will fix my problem, but I feel like I accomplished something getting rid of the codes I've been getting.

Also I was a little confused and I tested the voltage of the purge valve circuit while the PCM connector was connected and got 0.06 volts, whereas I get 0 volts with the connector disconnected. I believe I was supposed to test with the connector disconnected right?

So now that I fixed my EGR problem and my Purge valve problem where do I go from there? I'm still misfiring badly at 3k rpm.

Could something more internal like a fuel injector or piston be messed up? Could my block be cracked, i'm lost at what to do now

After reading all this. I see your car revs fine up to about 2500rpm's. Have you checked your TPS? Sometimes when they go bad it won't throw a code. But as you open the throttle the pot will reach bad spot and jump all over the place causing backfiring, hesitation and misfires. Maybe that's something to check out. If that scanner you have can graph the TPS slowly open the throttle as steady as you can and watch the graph. It should be a smooth line moving up. When you reach a bad spot the line will start jumping around.

I did compare parts at a few online stores for the MAF sensor to confirm that the s-10 and my car have the same MAF sensor.

On the TPS it isn't always at 2500 RPM, If I try flooring it it misses bad right off the get go and almost dies long before 2500 rpm, if I gradually apply throttle I can get to 3k rpm.

The car will die while idling sometimes when it is warmed up. I think it's more than a faulty sensor. It runs like this in closed or open loop.

I'm starting suspect fuel flow is the problem, I'm not sure if my fuel pressure is supposed to be 41-47 while running, or if its supposed to be a bit lower? I get 36 psi while running, I noticed if I rev up the engine then let off the gas the pressure drops down to 30 psi momentarily before building back up to 36.

I don't have any rfeally fancy equipment just stuff I borrowed from autozone.

I'm afraid to bring it to a shop because I worry they migh just go and replace tons of stuff before solving the problem, costing me way too much money.

I'm laid off right now and money is really tight.

Ok heres what we know, I think.

It's not the o2 sensor because it runs bad in open loop as well as closed loop.

It's not the catalytic converter because with the o2 sensor removed and the back pressure released it still runs the same. Same goes for backpressure released through removing the EGR valve.

It's not the MAF sensor because I replaced it with the same part number from another vehicle and it didn't make a difference. Also noting with the MAF unplugged it behaves differently but it's hard to tell with the problem being so severe as it is. It still idles fine without MAF hooked up.

It seems to be a problem isolated to 1 side of the Fuel trim? I'm not sure if the 2 sets of fuel trim refers to a trio of cyclinders or what? But Fuel trim 1 is always pretty normal, whereas fuel trim 3 is very far off? This has to mean something, most likely that that set of cyclinders has an air/fuel ratio problem.

This leaves us with a) not getting enough fuel flow to one half the engine. B.) Not getting good ignition off one half the engine. C) bad injectors or bad compression on one half of the engine.

Well does any of that seem to make sense, maybe I'm wrong about the fuel trim, but it seems this problem is happeneing on half the engine, causing issues with the fuel/air ratio there and the computer struggles to fix it but it is far too severe.

So maybe my fuel injectors on that half are bad, that fuel rail is clogged or faulty? I don't know, what do you guys think?

It doesn't really mater if I remove sensors or not, it still runs like crap when you rev it. I really think my fuel injectors are bad or some of the cylinders have bad compression.

And how do I go about replacing this throttle wire?

Ok scratch the throttle cable, I went to the hardware store and made my own.

Ok about the fuel trim, Since bank 3(there is no bank 2) is the one thats out of whack when the computer tried to fix it, thats obviously the side of my engine that is having problems probably, either bad injectors or something right? If my fuel pump wasn't putting out enough flow then both sides would probably have issues, If it was due to injection and I had a bad coil or something, then itd be one cylinder on each side.

This leaves me to believe I have bad compression on one of the cylinders of bank 3, or the fuel injector back there is bad or something along those lines.

So What Is my next step, or could it still be too little flow from the pump or a clogged fuel rail.

I still have decent engine fuel pressure I will pick up a vacuum guage and compression tester ASAP to test the back cylinders or the front ones, Im not sure what side TRIM 3 applies to.

Can you walk me through how to test compression and/or vacuum? And where can I find the proper specs?

Could a bad injector or low compression be causing these problems mainly only at 2500 rpm or higher?

Ok the egr system is fixed, I ran a test drive and the I/M monitor says EGR system OK. On my test drive I had no codes but many symptoms. I got out on the road and took off gradually like the GM OBD II drive cycle says, Got up to 55mph and put on cruise control and drove 4 miles or so at 58 mph. I then gradually decellerated down to 20 mph, turned around and this time applied about 3/4 throttle and it was misfiring badly in the 2.5k-3k range, never got higher than that. I then got up to 55mph and re-equipped cruise control, it went a little bit, then it bucked alittle bit, kicking cruise control off. I traveled back to my house then cruised down to a stop at my driveway. It bucked a few more times on the way in.

I noticed that went it bucks the tachometer goes from liek 2.5k rpm down to 2k then flucuates some more before the car stops bucking and missing and settles down to slowly resume acceleration again. Any of these driving symtpoms help anyone diagnosing the source of my problems?

Could it be that the plate the coil packs are sitting on has a crack and only seperates when the car is warm andthat is why the coil packs came back fine?

I have a 1998 Monte Carlo with 135,000 miles on it. I had issues with the Fuel Injectors years ago. Shuttering and shaking. I had one replaced and it was really expensive. Intially I was using Mobile Gas when I started having the problem. My husband didn't believe me when I said don't use the gas from that station anymore so he did and it messed my car up again and had to take it back to the shop. Had to take it back again because others were misfiring to. They put in fuel injector cleaner and I was told to use Shell Gasoline and I haven't had any problems since. For many many years. Only problem is my check engine light goes on all the time because of misfires. It has for years but the car is great and